Numerous processes are known for the preparation of toners such as, for example, conventional processes wherein a polymer is melt kneaded or extruded with a pigment, micronized, and pulverized to provide toner particles. In addition, various emulsion technologies, including phase inversion emulsification (PIE) and emulsion/aggregation (EA) methods, may be used with a polyester type polymer to provide toner particles. PIE methods involve converting a dispersed polymer in a hydrophobic organic solvent from a water-in-oil (W/O) emulsion to an oil-in-water emulsion (O/W), whereby the polymer is dispersed as latex particles. EA methods involve heating a polymer in water to form an emulsion of latex particles. With either technique, a colorant or a pigment may be added to the latex mixture, followed by the addition of an aggregating agent or complexing agent to form aggregated latex particles. The aggregated latex particles may be heated to allow coalescence/fusing, thereby achieving spherical aggregated, fused toner particles.
The vast majority of polymeric materials used in toners are based on fossil fuels, leading ultimately to an increase in greenhouse gases and accumulation of non-degradable materials in the environment. Recently, the U.S. Department of Agriculture (USDA) has proposed that all toners/inks have a bio-based content of at least 20%. Renewable or biodegradable reagents and materials, such as those that are plant-based/animal-based or that are readily biodegradable, are being investigated as replacements for current toner reagents that may be produced in a simplified manner at a low cost.
There remains a need for improved bio-based toner compositions suitable for high speed printing, particularly high speed monochrome printing that provide excellent flow, charging, lower toner usage, and reduced drum contamination.